Traditionally, the construction of control surfaces for aircraft has been from lightweight metal alloys. For example, for spoilers, frame elements, hinges, actuation fittings and sheet metal have been machined and assembled using appropriate fasteners, such as welding or rivets. Since spoilers are subjected to torsion during use, they are usually made in the form of a torsion box. Because of the many parts that must be assembled, the manufacture of the spoiler by traditional methods requires several machining and assembly steps and is accordingly quite expensive. In addition, at each place where individual parts are attached, there is a potential for failure of the weld or rivet at joint, which increases the possibility of failure of the part.
Composite materials of a cured resin and a reinforcing fiber have been used for certain parts in aircraft construction. Composites have high strength, and are light in weight, both which are desirable for aircraft. However, the use of composites for control surfaces has been limited. This is due in part to the difficulty of making large composite parts of complex configuration while maintaining the strict quality requirements required for aircraft parts. This problem is aggravated by the requirement of the shape of the spoiler, which requires a thick leading edge of high strengths for mounting of hinges and actuation fittings that tapers down to a thin trailing edge that must be of appropriate aerodynamic design. Adhering several pre-manufactured parts with a thermosetting resin can make large assemblies of composite materials. However, this would introduce undesirable points of weakness at the joints of the part, and require precision machining and fitting of the parts. In addition, any machining to form the part into their final shape, either for assembly to another part or for the final aerodynamic shape, is undesirable, for such will cut reinforcing fiber. Accordingly, undesirable weight in the form of extra reinforcing fiber must be added to compensate for the machining and the inherent weakness at joints. These problems have prevented composites from becoming a competitive replacement for metals on these parts, particularly in the commercial market where manufacturing costs must be kept low, and the very high performance required for military supersonic aircraft is not necessary.
It is accordingly, a long felt need in the industry to provide a method for making control surfaces, such as spoilers, that is competitive with traditional metal-assembly methods of the manufacturing, while providing improvements in strength, weight, and simplification of the manufacturing process.
Incorporation but reference
U.S. patent application Ser. No. 09/441,356, filed Nov. 16, 1999, U.S. patent application Ser. No. 08/839,110, filed Apr. 23, 1997, now U.S. Pat. No. 5,985,197 and U.S. patent application Ser. No. 08/865,493 filed May 29, 1997, are hereby incorporated by reference.
Objects of the Invention
It is, therefore, an object of the invention to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that solves the above problems.
Another object of the invention is to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that is integral in construction, and requires a little of no assembly of separate parts.
Another object of the invention is a to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that forms a part near its final shape that requires a minimum of machining.
Another object of the invention is a to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that allows the properties of each portion of the spoiler, such the leading and trailing edges, to be optimized for strength and light weight.
Another object of the invention is a to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that permits a torsion box construction to optimize the light weight and torsion properties of the spoiler.
Further objects of the invention will become evident in the description below.